Using trigonometry to calculate length

Using trigonometry to calculate length

Pencil and paper
Overview
Using this Resource
Connecting to the Curriculum
Marking Student Responses
Further Resources

Diagram of building

 

[Not drawn to scale]

 

a)
Jake measured the height of a building. He stood 30 m away and measured the angle to the top of the building as 58°.
Which method did Jake use to work out the height of the building (h)?
 
(A)   30 cos 58º          (B)   30 sin 58º          (C)   30 tan 58º           (D)   30 cosec 58º
 
(E)   None of these. The correct method is ____________________
 
 


Diagram of skateboard ramp

 

[Not drawn to scale]

 

b)
Whetu is building a skateboard ramp. He wants it to be at an angle of 24° and 2 m long.
Which method would Whetu use to work out the length of the base (b)?
 
(A)   2 cos 24º          (B)   2 sin 24º          (C)   2 tan 24º          (D)   2 cosec 24º
 
(E)   None of these. The correct method is ____________________
Task administration: 
This task can be completed using pencil and paper.
Level:
5
Description of task: 
Students choose the correct trigonometric ratio which would be used to calculate a missing length in two practical problems.
Answers/responses: 

 

Y11 (05/2000)

a)

C [Accept E and 30 ¸ tan 32º].

easy

b)

A [Accept E and 2 sin 66º].

moderate